Washington Government Printing Office, 1955
Buku Teks
Stebbins, Richard P., author
Harper & Row, 1963
Buku Teks
Stebbins, Richard P.
Harper & Brothers, 1955
Buku Teks
Pratt, Julius W., author
Prentice-Hall, 1965
Buku Teks
Government Printing, 1943
Buku Teks